<!-- demo.vue -->
<template>
  <div>
    <h3>父组件</h3>
    <hr>
    <Son1 @aaa="getData"/>
    <Son2 :msg="msg"/>
  </div>
</template>

<script> 

import Son1 from './Son1.vue';
import Son2 from './Son2.vue';
export default {  
   components: {
     Son1,
     Son2
   },
   
   data() {
     return {
       msg: '',
     }
   },

   methods: {
     getData(data) {
       this.msg = data;
     }
   }
};
</script>